Two HIV related proteins, TGF-beta1 and the HIV-1 protease, were studied by NMR spectroscopy. (1) TGF-beta1 structure. TGF-beta1 up and down regulates proliferation of HIV infected cells. In order to understand the activity of this multifunctional cytokine, we have undertaken to determine the solution structure of TGF-beta1 in solution. Previously we had determined the secondary structure of the protein in solution, and shown that the solution structure is in agreement with an independently determined X-ray structure of TGF-beta2, except in a domain that distinguishes the activities of the beta1 and beta2 isoforms. A low resolution folded structure of TGF-beta1 has been determined, and we are using the X-ray structure in further interpret our NOE data. We plan to make a detailed comparison of the three dimensional solution and crystal structures in order to derive a basis for understanding differences in function of the two protein isoforms. (2) HIV-1 protease. Several months ago we completed a material transfer agreement with the DuPont Merck Pharmaceutical Co. in which DuPont Merck agreed to provide Dr. Paul Wingfield of the NIH Protein Expression Lab with E. coli transformed to express high levels of HIV1 protease, as well as strong inhibitors of the protein. Dr. Wingfield has just supplied us with the first samples of the inhibited protease, and we have obtained high quality NMR spectra that show the protein to be properly folded an stable in solution. With a stable supply of high grade material available for the first time we are beginning 3- and 4-dimensional NMR experiments that will enable us to determine the 3D structure of the inhibited protease. The significance of this project arises from the unique, detailed structural information that is being obtained about HIV related proteins in solution. This information will form the basis for a rational drug design based upon the understanding of the function of these proteins in terms of interactions at the molecular level.